Intrinsic Josephson junctions in high-T/sub c/ superconductors as high frequency sources

We report on microwave emission experiments of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/-single crystals at frequencies between 12 GHz and 95 GHz. Due to the intrinsic Josephson effect these samples form series connections of typically 2000 contacts. For the first time we observed phase-locking of more than 1000 junctions at 93.7 GHz in Bi/sub 1.8/Pb/sub 0.2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/ single crystals. Concerning the development of high frequency sources we report on first experiments on vertically structured thin films of Tl/sub 2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/. >